1. Field of the Invention
The present invention relates to an electrophotographic apparatus in which consumables are collected into a sub-unit so that it may be replaceable, a main unit for the electrophotographic apparatus and a sub-unit thereof, and a method for identifying the sub-unit.
2. Description of the Related Art
Electrophotographic apparatuses such as a laser printer are well known. The electrophotographic apparatus includes many consumables such as a photosensitive drum and a developing device. For easy maintenance thereof by a user, the consumables are collected into a unit so that it may easily be replaced. That is, the electrophotographic apparatus is divided into a main unit and a sub-unit into which the consumables are collected so that the sub-unit may be replaced for easy replacement of the consumables.
The sub-unit expires in service life as it is used for a certain period and then cannot achieve the expected performance. The main unit, monitors the quantity of the sub-unit consumed to prompt the user to replace it before its service life expires. The consumed quantity of, for example, the sub-unit is monitored on the basis of the number of sheets of images formed using this sub-unit. That is, the consumed quantity of the sub-unit is monitored by counting the total number of printed sheets from the timing the sub-unit is attached. To correctly monitor the consumed quantity of the sub-unit, therefore, it is necessary that the unused sub-unit is attached. For this purpose, it has conventionally been decided whether the attached sub-unit is not used yet, when the sub-unit is attached.
As techniques for deciding whether or not the attached sub-unit is unused, there are known Jpn. Pat. Appln. KOKAI Publication No. 6-118736 and Jpn. Pat. Appln. KOKAI Publication No. 2000-29369.
According to the technology disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-118736, the sub-unit is fitted with an electronic element such as a fuse so that whether the sub-unit is unused is decided on based on conduction/nonconduction of the electronic element. That is, first, each sub-unit is fitted with an electronic element capable of continuity, after the sub-unit is attached to the main unit, the electronic element is destroyed to provide discontinuity. By this, it is possible to decide that the sub-unit is unused if the electronic element is continuous. If it is not continuous, on the other hand, the sub-unit is decided to be already used.
According to the technology disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2000-29369, each sub-unit is fitted with a barcode label, whereby whether the sub-unit is unused is decided on based on the information carried by this barcode label. That is, the sub-unit is decided to be unused if the information of the bar code label read out from the sub-unit differs from that read out previously and, otherwise, it is decided to be used already.
There are known other similar examples of mounting a non-volatile memory for permitting the sub-unit to have identification information.
By the technology disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-118736, however, the electronic element may not securely be destroyed depending on characteristics or fluctuations of the electronic element. In such a case, this electronic element is, when the sub-unit carrying it is attached to the main unit again, continuous electrically, so that the main unit may mistakenly decide that the sub-unit is unused.
By the technology disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2000-29369 or by a memory mounting technology, on the other hand, the relevant configuration and processing becomes complicated. Moreover, the number of the interface signals transferred between the main unit and the sub-unit is increased, thus increasing the costs and grading the reliability problematically.
It is an object of the invention to make it possible to securely decide whether a sub-unit is unused with a simple configuration.
One aspect of this invention provides such an electrophotographic apparatus as follows.
An electrophotographic apparatus, having a main unit and a sub-unit which is attachable, in such a way that it may be detached, to the main unit arbitrarily, for using the sub-unit in the main unit to thereby form an image, comprising: a resistive element which is fitted to the sub-unit and which is made of such a material that is changed in conductivity when exposed; an exposure section configured to expose the resistive element when the sub-unit attached to the main unit enters a predetermined operative state; a detection section configured to detect a conductivity of the resistive element fitted to the sub-unit attached to the main unit; and an identification section, provided on the main unit, configured to decide whether, as the attachment of the sub-unit is made, the attached sub-unit is unused on the basis of the conductivity detected by the detection section.
A main unit which, when a sub-unit fitted with a resistive element made of such a material that is changed in conductivity when exposed is arbitrarily attached thereto, constitutes an electrophotographic apparatus together with the sub-unit, comprising: a detection section configured to detect a conductivity of the resistive element fitted to the sub-unit attached; and an identification section configured to decide whether, as the attachment of the sub-unit is made, the attached sub-unit is unused on the basis of a conductivity detected by the detection section.
A sub-unit which is arbitrarily attached to a main unit and which constitutes an electrophotographic apparatus together with the main unit in order to enable image formation by the main unit, the sub-unit including a resistive element made of a material which is changed in conductivity when exposed.
An identification method for performing the identification of a sub-unit fitted with a resistive element made of a material which is changed in conductivity when exposed, by a main unit which forms an image by utilizing the sub-unit and also which constitutes an electrophotographic apparatus together with the sub-unit when the sub-unit is arbitrarily attached thereto, the method comprising: detecting a conductivity of the resistive element fitted to the sub-unit attached; and deciding, as the attachment of the sub-unit is made, whether the attached sub-unit is unused on the basis of the detected conductivity.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.